As is known, many pourable food products, such as beverages, fruit juice, pasteurized or UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.
A typical example of this type of package is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing laminated strip packaging material.
The packaging material has a multilayer structure substantially comprising a base layer for stiffness and strength, which may comprise a layer of fibrous material, e.g. paper, or mineral-filled polypropylene material; and a number of layers of heat-seal plastic material, e.g. polyethylene films, covering both sides of the base layer.
In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of gas- and light-barrier material, e.g. aluminium foil or ethyl vinyl alcohol (EVOH) film, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
As is known, packages of this sort are produced on fully automatic packaging machines, on which a continuous tube is formed from the web-fed packaging material; the web of packaging material is sterilized on the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is completed, is removed from the surfaces of the packaging material, e.g. evaporated by heating; and the web of packaging material so sterilized is maintained in a closed, sterile environment, and is folded and sealed longitudinally into a tube.
The tube is filled with the sterilized or sterile-processed food product, and is sealed and cut along equally spaced cross sections to form the packages.
Units are known, for example from Italian Patent application TO2007A000677 in the name of the same Applicant, for transferring and up-ending sealed packages of pourable food products.
More specifically, such units transfer the packages successively along a path from an infeed station to an outfeed station, and simultaneously up-end the packages from an infeed position, in which the packages are positioned with their axis tilted relative to the horizontal, into an outfeed position, in which the packages are positioned with their axis substantially vertical.
Known units receive the packages at the infeed station from a first conveyor, and feed them to a second conveyor at the out-feed station.
More specifically, the first conveyor supplies the up-ending and transfer unit with packages in the infeed position, and the second conveyor withdraws the packages from the unit in the out-feed position.
The known units substantially comprise a rotary member having a number of push arms which receive respective packages at an infeed station of the path and cooperate with respective packages to push them along the path; and two fixed rails extending substantially along the path and cooperating with the packages to ease them from the tilted infeed position to the out-feed position.
In detail, each push arm is articulated relative to the rotary member and comprises a respective cam follower which interacts with a fixed cam for gradually varying its inclination relative to the rotation axis of the rotary member along the path from the infeed position to the out-feed position.
More specifically, the push arms are elongated along respective first directions.
Still more precisely, the projections of the first directions on a plane orthogonal to the rotation axis of the rotary member extend radially to the same rotation axis.
Furthermore, the projections of the axes of the packages on the above-identified plane are skew relative to the rotation axis of the rotary member.
In other words, the projections of the axes of the packages are not radial to the rotation axis of the rotary member.
Though efficient, units of the above type leave room for improvement.
More specifically, the Applicant has observed that, due to the above configuration of the push arms, the thrust exerted by the push arms is not perfectly uniform on the faces of the respective packages.
There is therefore the risk that the packages are not fully controlled when pushed by respective push arms.
As a result, there is the risk that the packages jam inside the unit, thus interrupting the operation of the packaging machine.
A need is therefore felt within the industry to reduce as much as possible the risk that the operation of the packaging machine is interrupted.
Furthermore, there is the risk that the not perfect uniform contact between each push arm and the abutting surface of the respective package generates a stress on those respective packages, especially at high productivity rate of the packaging machine.
Accordingly, there is the risk to penalize the final shaping quality of the packages, especially at high productivity rates of the packaging machine.
A need is therefore felt within the industry to increase, as much as possible, the final shaping quality of the packages, especially at the above-mentioned high productivity rates.